1. Field of the Invention
The present invention relates to an image sensing apparatus that obtains an image by image sensing and applies electrical blur correction processing to the image, and an image sensing method for the image sensing apparatus.
2. Description of Related Art
Among image sensing apparatuses capable of image sensing still images exemplified by digital cameras, ones that correct motion thereof (so-called camera shake) on image sensing have been widely used. For example, some adopt optical correction processing in which an optical system such as a lens is driven to correct an optical image itself incident thereon, and others adopt electrical correction processing in which correction is applied to an image obtained by image sensing. In particular, attention is paid to those provided with electrical correction processing function, because they do not need to be provided with components such as a motion sensor and a driving system, and thus can be made compact.
An example of electrical blur correction processing is one that uses image merging. In the blur correction processing using image merging, a plurality of images are merged together to obtain an image containing less blur. In this type of blur correction processing, the amount of blur is reduced by merging an image that is sensed with a longer exposure time (hereinafter referred to as second image) and an image that is sensed with a shorter exposure time (hereinafter referred to as first image).
The second image contains blur but contains less noise. On the other hand, the first image contains less blur but contains more noise. Thus, an image containing less blur and less noise can be obtained by merging these images together.
However, there may be a case in which even the first image contains more blur. Examples of such a case include a case of a long focal length (a high optical zoom magnification) and a case in which the exposure time for even the first image as well as that for the second image needs to be long because the subject is in a dark environment. As in these cases, if even the first image contains a large amount of blur, the resultant merged image also contains a large amount of blur, and thus, inconveniently, the amount of blur cannot be sufficiently reduced.